perf is a tool for profiling on linux.

You can import profiles into speedscope which were recorded using perf record and formatted using perf script.

perf record -a -F 999 -g -p PID > perf.data
perf script -i perf.data > profile.linux-perf.txt

Then drop the resulting perf.txt into speedscope, or if you have speedscope installed locally, you can run:

perf record -a -F 999 -g -p PID > perf.data
perf script -i perf.data | speedscope -